that similar species utilize the same kind of space. Priority of 

 arrival as recruits, rather than subtle differences in ecological 

 requirements or competitive abilities as adults, appears to 

 determine which species occupy each site (Sale 1978) . Thus, 

 Natural Selection should favor those individuals of a species who 

 maximize the return of their offspring to home reefs. Sale's 

 lottery hypothesis has stirred considerable debate (Smith 1978, 

 Dale 1978, Anderson £t al. 1981) . It is clear that the resolu- 

 tion of whether to accept or reject it as a viable hypothesis 

 lies, in part, in determining the fate of the planktonic larvae 

 in the ocean currents (Helfman 1978, McFarland 1982). 



Even though an extensive literature deals with the genetics 

 and evolutionary consequences of dispersing offspring (Gadgil 

 1971) , little strategic sampling has been done to ascertain the 

 frequence of dispersal in natural animal populations in general, 

 and in marine populations in particular (Leis 1983) . Recent 

 advances in knowledge of the ocean circulation make this just now 

 a feasible scientific undertaking. 



The Hawaiian fauna has a high percentage of endemic species, 

 emphasizing that many species have clearly delineated and limited 

 distributions. Conversely, the life history strategy of some 

 species may be to colonize distant habitats. A mechanism whereby 

 such larVae are transported en masse would increase the chance of 

 successful colonization elsewhere. Hawaiian eddies appear to 

 remain stationary near the islands up until several months and 

 then, perhaps, to move off into the open ocean. Thus, eddy 

 mechanisms could be responsible for transporting fish larvae 

 through the open ocean as well as maintaining populations near 

 shore. Any feature of the ocean circulation which would accumu- 

 late larvae is likely to accumulate other planktonic particles 

 also. Larvae in eddies are transported in microcosm ecological 

 communities (Wiebe e_t al. 1976, Wiebe 1976, Ortner £t al. 1978). 

 The duration of existence and extent of movements of eddies are 

 important factors determining whether or not eddies function to 

 retain plankton near islands or to transport plankton away. An 

 especially important relationship which needs to be examined is 

 the comparative lifetimes of mesoscale eddies and the planktonic 

 phase of shore fishes. 



FISH LARVAE IN EDDIES 



We have investigated whether or not offshore ocean eddies 

 near Hawaii play a key role in the life cycle of coastal marine 

 species by functioning to retain planktonic larvae near the 

 islands until such larvae metamorphosize and return to inshore 

 habitats. In general, the peak period of eddy formation and 

 movement appears to coincide with the peak season of reproduction 

 by Hawaiian shore fishes. In the following sections we will 

 develop the ideas, discuss the mechanisms related to the proto- 

 type model, and present relevant biological and physical evi- 

 dence. We will present preliminary results of our field investi- 

 gations at the December 1983 meeting of the ASZ. 



The possibility that ocean eddies near islands might func- 

 tion as reservoirs for planktonic larvae of coastal species was 



32 



